Size: |
Rice weevils are about 1/8 in (3-4 mm) long. |
Characteristics: |
Adult's wing covers usually have 4 faint red to yellow pale marks;
deep pits on thorax are round or irregular in shape; the midline of
the pronotum is usually puncture-free. Wings are fully developed,
used for flight. Male's snout is shorter, wider and with more distinct
punctures than female's. Larva is legless, thickened in the middle
for a humpback look, and fairly smooth; with 7-8 tiny fingerlike sensory
projections on the lower mouthpart. |
Color: |
Adult is dull reddish brown; larva is creamy white with brownish-black
head. |
Geographic Range: |
The rice weevil is found all over the world, especially in warm
climates. In the U.S. it is widely distributed in field and stored
grain in the south, but only in stored grain to the north of North
Carolina. |
Comparison with other species: |
It takes an expert to tell the difference between a rice weevil
and a maze weevil. The granary weevil does not have pale areas on
wing covers, and the pits on the thorax are elongated in shape. The
broadnosed grain weevil has a short broad snout, the length being
approximately twice the width, or less. |
Habitat: |
Home Sweet Home = Rice Sweet Rice (or corn, or wheat). |
Food: |
Corn, wheat, rice, rye, buckwheat, cereals, beans, nuts, cotton,
grapes, apples, pears. |
Biology: |
The rice weevil female bores a hole in kernel of grain, lays an
egg, then seals the hole with a gelatinous material. She lays 300-400
eggs in a lifetime, but seldom in winter. The cooler the temperature,
the less egg-laying there is. Larvae go through 3-4 stages (instars)
in about 18 days, and pupate for about 6 days. The adult rice weevil
stays in the grain kernel for 3-4 days until it is hardened and mature.
The complete life cycle can be as short as 32 days in summer. Adult
may live 3-6 months. |
Invasion: |
In southern U.S. adult rice weevils fly from stored grain to the
crop in the field, which in turn goes into storage, continuing the
infestation. Adults are also attracted to light. |
Damage: |
Rice weevils are important destroyers of crops and stored grain. |
Prevention: |
- Inspect incoming items.
- Supply ventilation.
- Keep buildings in good physical condition to reduce entry.
Sanitation:
- Quickly remove spilled grain.
- Keep grounds and facility generally clean.
- Store pallets 18 inches away from walls, torn packages replaced.
- Rotate food and nonfood stock. Rotate oldest stock out first.
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